Spinal fusion surgery is known, in which spacings between a plurality of vertebrae are held, a spinal fixation tool such as a spinal screw is engaged with each vertebra to relax the pressure on the nerve, and a plurality of spinal fixation tools are coupled to each other with rod members. There is known a mode of attaching a spinal fixation holding device to the proximal end portion (head portion) of each spinal fixation tool to hold the spinal fixation tool, used for such spinal fusion surgery, when fixing the spinal fixation tool to the vertebra (see, for example, PTL 1).